This Swedish composer earned a lot of attention with last year's blackened drone opus Kontrapoetik, but Horn has been a significant figure in European underground music circles for quite a while (she co-runs the XKatedral label with Kali Malone, for example). On her latest album, however, she seamlessly slips into somewhat different stylistic territory than I expected, as Epistasis is shaped by some very intriguing and inventive compositional techniques (one of which draws its inspiration from Arvo Pärt). And much like Pärt (and Malone), Horn has found a unique way to use traditional classical instrumentation that does not bear much resemblance to the current classical/neo-classical milieu at all. There are still some lingering shades of Horn's darker, heavy influences to be found as well, but the most striking creative breakthrough on the album comes in the form of the tender, twinkling, and intricately arranged two-part piano suite "Interlocked Cycles."

The heart of Epistasis, "Interlocked Cycles," was originally composed for a larger audiovisual work that premiered last year at Stockholm's Royal College of Music. Sadly, I have not yet figured out a way to sync up the lights in my apartment to recreate the full multisensory experience of that night, but the music is nevertheless quite beautiful in decontextualized form. Curiously, the two halves of the piece are the album's bookends, so they are presumably intended as discrete entities. They were composed using roughly the same ideas though: Horn used a computer-controlled piano to achieve a steady escalation of both tempo and density. There is also some phase manipulation involved. In more practical terms, the opening "Interlocked Cycles I" resembles an ingenious, large-scale music box: it opens quite simply with a lone, somber arpeggio, yet steadily becomes warmer, brighter, and more lovely as more moving parts are triggered and lock into place. By the end, it is a complex lattice of intertwined, rippling melodies and it is absolutely heavenly, though subterranean drones and eerily whining electronics provide enough unease to ensure that a subtly haunted mood still gnaws at the fringes of the idyll. That same structural arc repeats for the closing "Interlocked Cycles II," but it takes a considerably different shape, as there is a steadily intensifying sense of drama and grandeur in the underlying chord progression. While it is not quite as strong as its predecessor on the whole, the final moments achieve a mesmerizing level of quiet intensity after the chords fall away. I also appreciated the added textural flourish of rattling, muted notes (presumably from piano strings covered with foil or something similar).

The two pieces in the middle of the album take divergent paths of their own. On "Epistasis," for example, Horn replicates the roiling grandeur of black metal with a double string quartet and some overdubbed guitar noise. It is quite a sweeping and cinematic piece that evokes sinister castles on windswept crags, which normally tends to be the sort of thing that does not appeal to me very much. To her credit, however, Horn almost wins me over to her brand of orchestral doom with the occasional curdled note and an undercurrent of more nuanced emotions. Thankfully, the following "Konvektion" resonates with me on a much deeper level, recalling the sublime organ minimalism of Horn's longtime collaborator Kali Malone. Horn differs significantly from Malone in her approach, however, as she works her harmonic magic out in the open and seems far more amenable to lushness and layering. The two artists are very similar in their compositional inventiveness and rigor though. Case in point: "Konvektion" was written for two organists (sharing an instrument) using Arvo Pärt's "tintinnabuli" approach, but with the twist that the chord durations are dictated by the breathing patterns of each individual performer. In Horn's hands, tintinnabular music is less fragile and melodic than it is in classic Pärt fare like "Spiegel im Spiegel," yet "Konvektion" achieves something similarly appealing with its enhanced harmonic depth and languorously organic arc.

With Epistasis following on the heels of Malone's excellent The Sacrificial Code, this is shaping up to be quite an impressive year for Stockholm's experimental music scene and I am now very curious about what the rest of duo's regular collaborators have in the pipeline (Malone and Horn are part of a quartet that also includes Ellen Arkbro and Marta Forsberg). In the hyperconnected cultural landscape of the internet age, it is truly rare for a regional scene to blossom with its own distinct character, yet something quietly radical and exciting has unquestionably taken shape from such an improbably smart and idiosyncratic bunch of artists all playing together and exchanging unconventional ideas. I cannot think of any other milieu that an album like this could have emerged from. With Epistasis, Horn has made the impressive leap from "fine drone artist with some cool conceptual ideas" to "formidable composer that other artists will absolutely try to emulate." This album's success goes deeper than just great ideas and skillful execution though, as Horn has found a near-perfect balance between the soulful and the cerebral and applied it to classical instrumentation in a way that is appealingly melodic, timeless, and distinctive. I am properly floored by the rapid and wonderful evolution that Horn's work has undergone since just last year: Kontrapoetik was a strong album, but this one is on an entirely different plane altogether.